Ball nut and lever steering gear



P 1954 c. w. LINCOLN BALL NUT AND LEVER STEERING GEAR 2 Sheets-Sheet 1Filed Oct. 18, 1951 ATTORNEYS P 4, 1954 c. w. LINCOLN 2,688,885

BALL NUT AND LEVER STEERING GEAR Filed Oct. 18, 1951 2 Sheets-Sheet 2//z W #7 6 T W i. W g I //Z' i 15/5 I 3 A?! Q I a 2- I li? I IN V EN TOR94M ATTORNEYS Patented Sept. 14, 1954 UNITED STATE$ PATENT DFFICE ClovisW. Lincoln, Saginaw, Mich, assignor to General Motors Corporation,Detroit, Mich, a

corporation of Delaware Application October 18, 1951, Serial No. 251,894

(Cl. M -499) 14 Claims. 1

This invention relates to steering gears for motor and other types ofvehicles and more particularly to steering gears of the ball nut andlever type.

In steering gears of the ball nut and lever type anti-friction means areprovided between the contacting parts thereof to reduce friction andthereby enable efficient operation thereof. In order to reduce frictionto a minimum, clearance must be provided between yokes mounted on thepitman shaft and the trunnions on the ball nut. This clearance in somecases may cause undesirable lost motion between the yokes and trunnionswhen the steering gear is in its centered position. Another difficultyencountered in prior constructions is the tendency of the steering gearto move past its centered position during movement of the steering wheelto straighten the vehicle after a turn has been efiected.

One object of the present invention is to provide a novel and improvedsteering gear which is so constructed that substantially no lost motionexists between the nut and pitman shaft when the steering gear is in itscentered position.

Another object is to provide in a steering gear of the stated charactermeans for dampening the movement of the operating parts as they approachtheir centered position.

A further object is to provide in a steering gear of the ball nut andlever type, anti-friction means between the engaging parts thereofwhereby maximum efficiencies in operation are obtained.

A more specific object is to provide in a steering gear of the ball nutand lever type, a pair of anti-friction trunnions on the ball nutengageable with yokes secured to the pitman shaft and to provideadjustable ramp means on at least one of the arms of said yokes which isadapted to engage the associated trunnion -when the steering gear is incentered position thereby preventing lost motion between the saidtrunnion and yoke when the steering gear is in said centered position ofadjustment.

A still further object is to provide means between the ball nut and thepitman shaft of a ball nut lever type of steering gear which preventsundue turning of the nut about the worm.

A still further object is to provide a steering gear of the statedcharacter which is simple in construction, economic in manufacture andhighly efficient in operation.

Other and further objects will become apparent as the description of theinvention progresses.

Of the drawings:

Fig. 1 1s a longitudinal sectional view taken through the lowerextremities of a steering shaft showing the construction of the ball nutand lever and the specific operating connections therebetween, certainparts being broken away to more clearly show the structure of certainelements thereof.

Fig. 2 is a transverse sectional view taken substantially along line 2-2of Fig. 1.

Fig. 3 is a sectional view taken substantially along line 33 of Fig. 1.

Fig. 4 is a transverse sectional view similar to Fig. 2 but showing amodified construction, and

Fig. 5 is a fragmentary view partly in section taken substantially alongline '5--5 of Fig. 4.

Referring to the drawings the numeral 69 indicates generally a portionof a steering gear of the bali nut and lever type comprising a steeringshaft 78 having a worm 12 provided at one end thereof. The worm portion72 of shaft H1 is mounted in thrust roller bearings 74 and 76 providedat the opposite ends of an enclosing housing #8. Mounted on worm 72 is aball nut structure til which is adapted for substantially nonrctatablemovement between the ends of worm l2. The specific construction of worml2 and ball nut 80 and the method of operation thereof is old in the artand, accordingly, a detailed description thereof will not be givenherein. For a complete disclosure of such a mechanism reference may behad to United States Patent 2,380,- 662 granted to R. P. Means, Jr., onJuly 31, 1945. Suffice it to say that upon rotation of shaft 10 in onedirection nut structure 80 will move to the left (Fig. 1) and uponactuation of said shaft in the reverse direction the nut structure willmove to the right, the balls 8| disposed between the said nut and wormproviding a highly eflicient anti-friction bearing therefor. Mounted atthe opposite sides Hi3 and I of nut structure and in axial alignment area pair of anti-friction trunnions Hi4 and H36. Anti-friction trunnionsEat and H36 extend into spaced yokes or bifurcated arms 38 and 953,respectively, secured to and extending outwardly from a pitman shaft 84.As shown in Fig. 2, a roller I66 is mounted in a needle-type rollerbearing H16 provided on trunnion H36. Trunnion lil l has a similaranti-friction roller Hid mounted thereon. Pitman shaft 84 is disposed atsubstantially right angles to worm l2 and is mounted at one end in aneedletype roller bearing [4| provided in the cover 18 of housing 76 andat the other end in a second needle type roller bearing I39 provided inthe tubular extension I36 of said housing. Pitman shaft 84 is heldagainst axial movement in one direction by a stud bolt 78 makingthreaded engagement with a tapped opening provided in the ofiset portion18 of cap I8. Bolt 18* is secured in adjusted position by a lock nut 78The pitman shaft 84 is held against axial movement in the oppositedirection by the flange portion 90 of arm 88. Flange 80 lies adjacent anannular boss 80 provided interiorly of casing I8, a gasket or washer 98being provided between said flange and boss. A pitman arm I42 is splinedto the lower end I43 of pitman shaft 84 and is held thereon by lock nutI44.

The anti-friction trunnions I04 and E06 and the arms I88 and H of yokes88 and 90, respectively, are so designed that a very slight amount ofclearance is provided therebetween. Consequently, upon axial movement ofnut 80 along worm T2, rolling contact is provided between said trunnionsand the arms of yokes 88 and 90.

In order to prevent turning of nut structure 80 about worm I2 duringoperation of the device, a semicylindrical member 82 is mounted on theportion 86 of pitman shaft 84 disposed between the forked arms 88 and 90thereof. The portion 86 of pitman shaft 84 has provided intermediate theends thereof a pair of diametrically opposed circular recesses 92. Theportions of the edges of semicylindrical member 82 lying adjacent torecesses 82 are punched inwardly, as shown at 94, so as to enter saidrecesses slightly thereby effectively securing said member on the pitmanshaft 84. Semicylindrical member 82 has provided near each end thereof asemicylindrical flange 96 which is adapted to lie in slightly spaced re-1 lation with a smooth, flat oifset portion 88 provided on the innersurface I00 of nut structure 80. The flanges 96 cooperate with thesmooth surfaces 98 on nut structure 80 to prevent undue turning of thelatter about worm I2 during travel thereof in either direction along thesaid nut. Binding or scuffing of the trunnions and the bifurcated armson pitman shaft 84 is thus prevented and proper operation is assuredunder all conditions of operation.

One of the arms I08 and H0 of each of the forked arms or yokes 88 and 80is provided with adjustable means to take up the clearance between thetrunnions I04 and I06 and the said forked arms when the steering gear isin centered position. Inasmuch as the structure of the adjustable meansprovided on each of the arms I08 and H0 is identical, a description ofthe adjustable means associated with one of the arms I08 will sufficefor both.

Arm I08 of forked arm 88 is provided with an internally threaded boreII2 for receiving a retaining bolt I I4 for a longitudinally adjustablemember IIB. As shown more particularly in (Fig. 1, member H6 is ofsubstantially L-shaped construction having one leg II8 abutting theinner surface I20 of arm I08. The outer surface of leg H8 is .adapted toengage trunnion I04 and for the greater part of its length lies insubstantially parallel relation with the inner surface of the oppositelydisposed arm I08 of yoke 88. Leg II8 of yoke 88 terminates at its innerend in a ramp I22. The other leg I24 of adjustable member I I6 isdisposed at substantially right angles to leg I I8 and is provided withan opening centrally thereof for receiving bolt I I4. The inner surfaceof leg I24 is provided with a recess I26 for receiving a threadedretaining member I28. A lock nut I30 provided at the outer end of boltII4 cooperating with retainer I28 effectively holds the outer end ofadjustable member II8 against movement. The upper end of the innersurface of leg II8 has provided therein a slot I32 which receives theinner end of a pin I3 4 extending through a transverse opening providedin arm I08. The adjustable member H8 is guided for movement lengthwiseof arm I08 by a substantially U-shaped retaining member I36. The inneredges of retaining member I38 are provided with inturned flanges I38which extend into longitudinally disposed grooves I40 provided at theopposite sides of the leg II 8 of adjustable member II6. Member I36 alsoengages the outer end of pin I34 to prevent movement of the latter outof recess I32. To adjust member IIB, lock nut I30 is simply loosened andthe bolt is then turned in the proper direction.

It is apparent that by adjusting member I I6 in this manner the ramp I22thereon may be brought into engagement with trunnion I04 when thesteering gear is at or near its centered position. At this time theopposite side of trunnion I04 is in or nearly in engagement with theinner surface of the opposite arm I08 and by adjusting member II6 inthis manner all slack or clearance between yoke 88 and trunnion I04 maybe eliminated. A slight clearance is desirable between the trunnions andthe inner surfaces of their yokes. However, it is also desirable tominimize or eliminate this clearance when the steering gear is incentered position to prevent backlash and thereby insure efiicientoperation.

Should it be desired to dampen the movement of the steering gear in itscentered position the member H8 may be so adjusted as to causeengagement of ramp I22 with trunnion I04 just before the steering gearreaches its centered position. As the steering gear approaches. centeredposition, pressure would then be exerted on the worm I2 by trunnion I04resulting in dampening the movement of said steering gear. If desired,dampening movement might also be produced by enlarging the thread onworm 12 at the center thereof to preload the balls 8| when the steeringgear is in centered position, the said balls otherwise being free ofsuch loading action.

In order to compensate for wear during operation of the device, theentire contacting surface of the leg II8 of adjustable member II6 may beadjusted laterally. This may be done by simply providing inclinedcontacting surfaces between the inner surface of arm I08 and the innersurface of the leg I I8 of adjustable member I I6. By so constructingthe parts, it is clear that upon adjustment of member II6longitudinally, the latter will move laterally toward or away from theopposite arm I08 of yoke 88 depending upon the direction in which themember H6 is adjusted. A ramp similar to ramp I22 may also be providedin an adjustable member so constructed.

Figs. 4 and 5 disclose another embodiment of the invention. Instead ofproviding spaced flanges on the pitman shaft for preventing turning ofthe nut, such as the flanges 96 on member 82, the structure shown inFigs. 4 and 5 employs a somewhat different construction. As shown inFig. 4 the side I48 of ball nut structure I50 adjacent anti-frictiontrunnion I52 has provided, at opposite sides of the latter, a pair offlat smooth shoulders I54 and I56 which lie closely adjacent to theunder surface I 58 of one of the forked arms or yokes I60 secured to thepitman shaft 162. The other forked arm or yoke I64 which receivesanti-friction trunnion I66 is spaced a greater distance from theopposite side I68 of nut 15c. Trunnions I52 and I66 extend between thebifurcations of arms I66 and I64, respectively, a slight amount ofclearance being provided to insure proper rolling contact of saidtrunnions on said arms. The upper end I16 of pitman shaft I62 isprovided with a T-slot I12 for receiving the head I14 and shank I16 ofan adjusting bolt I18 making threaded engagement with a tapped openingprovided in the cover I19 of easing MB. A lock nut I86 holds the partsin adjusted position. By adjusting bolt I18 pitman shaft I62 may beadjusted so that a slight clearance is provided between shoulders I54and IE6 on ball nut structure I60 and the inner surface I58 of yoke I66.In this construction the upper end of pitman shaft I62 is mounted in aneedle-type roller bearing I62 provided in cover I19 of casing I49. Theother end of shaft I62 is mounted in spaced needle bearings I84 and I86provided in the tubular extension ISB of casing I49. A seal I60 isprovided between the lower end of tubular extension I68 and shaft I62 toprevent the escape of lubricant from within the casing. A pitman arm I92is splined tothe lowermost end I9 1 of shaft I62 and is held in placethereon by lock nut I96. I

By adjusting the pitman shaft I62 by bolt I18 as just described, properclearance between nut I50 and arm I66 may be provided. The shoulders I54and I56 on nut I56 function to prevent undue turning of the latter aboutworm I82, whereby binding and scuffing of the parts is prevented. Inthis construction also, when the ball nut structure I50 approaches itscentered position on worm I82 it may turn slightly about worm I62bringing one of the shoulders 154 or 156 into contact with the surfaceI58. This causes a slight friction between the parts but is notsufficient to in any way cause binding or scuffing of the parts. Themovement of the steering gear may be dampened by simply enlarging thethread of screw I82 intermediate the ends thereof to preload the ballsI5I. When the nut moves away from centered position free movement or theballs I5I may take place.

From the foregoing description it is seen that novel and simplifiedmeans have been provided for preventing turning of the nut about itsshaft and thereby avoiding undesirable binding or scuffing of thetrunnions in the yokes. Novel means have also been provided forpreventing clearance between the trunnions and the yokes when thesteering gear is in centered position and also for dampening the actionof a steering gear as it approaches its centered position.

While the invention has been described in connection with steering gearsfor motor and other vehicles, it is apparent that the invention isequally adaptable for other uses wherein power transmission is desired.It will also be apparent that the invention as shown and describedherein is subject to modification and change without departing from thespirit thereof. It therefore is to be understood that it is not intendedto limit the invention to the embodiments shown and described herein butonly by the scope of the claims which follow.

I claim:

1. Power transmitting means comprising, a worm, anti-friction bearingsfor said worm, a ball nut mounted on said worm, a rock shaft disposed atsubstantially right angles to said worm, anti-- friction bearings forsaid rock shaft, one or more bifurcated arms secured to said rock shaft,one or more trunnions mounted on said nut, one for each of said arms,anti-friction means on said trunnions providing rolling contact betweensaid trunnions and said arms, and means for dampening the movement ofsaid nut in one position of adjustment.

2. Power transmitting means comprising, a worm, anti-friction bearingsfor said worm, a ball nut mounted on said worm, a rock shaft disposed atsubstantially right angles to said worm, antifriction bearings for saidrock shaft, one or more bifurcated arms secured to said rock shaft, oneor more trunnions mounted on said nut, one for each of said arms,anti-friction means on said trunnions providing rolling contact betweensaid trunnions and said arms, means for dampening the movement of saidnut in one position of adjustment, and means on said rock shaft and nutfor preventing undue turning movement of said nut about said worm.

3. Power transmitting means, comprising, a worm, a nut movable on saidworm and adapted for movement from a starting position thereon topositions on either side of said starting position, a rock shaftdisposed at substantially right angles to said worm, a pair of spacedbifurcated arms secured to said shaft, a pair of trunnions secured tooppositely disposed sides of said nut and extending between thebifurcations of said arms, clearance being provided between saidtrunnions and bifurcations to prevent undue friction therebetween, andmeans for eliminating said clearance when said nut reaches the saidstarting position.

4. Power transmitting means, comprising, a Worm, a nut movable on saidworm and adapted for movement from a starting position thereon topositions on either side of said starting position, a rock shaftdisposed at substantially right angles to said worm, a pair of spacedbifurcated arms secured to said shaft, a pair of trunnions havinganti-friction rollers thereon secured to oppositely disposed sides ofsaid nut and extending between the bifurcations of said arms, clearancebeing provided between said trunnions and bifurcations to permit rollingcontact of said trunnions on said arms, and adjustable means foreliminating said clearance between said trunnions and bifurcations whensaid nut reaches the said starting position.

5. The invention set forth in claim 4 wherein said adjustable meanscomprises a member disposed along the inside of one of the bifurcationsof at least one of said bifurcated arms and adapted to be engaged by theassociation of said trunnions, means for adjusting said member, andmeans for retaining said member in position.

6. Power transmitting means, comprising, a worm, a nut movable on saidworm and adapted for movement from a starting position thereon topositions on either side of said starting position, a rock shaftdisposed at substantially right angles to said worm, a pair of spacedbifurcated arms secured to said shaft, a pair of trunnions havinganti-friction rollers thereon secured to oppositely disposed sides ofsaid nut and extending between the bifurcations of said arms, clearancebeing provided between said trunnions and bifurcations to permit rollingcontact of said trunnions on said arms, and adjustable means foreliminating said clearance between said trunnions and bifurcations whensaid nut reaches said starting position, said adjustable meanscomprising, a movable facing member disposed along the inside of one ofthe bifurcations of at least one of said arms having an inwardlyinclining ramp portion at one end thereof adapted to engage saidtrunnion, and means for longitudinally adjusting said member.

'7. In a steering gear, the combination of a steering shaft, a worm onsaid shaft, a ball nut mounted on said worm and adapted for movementfrom a starting position on the latter to positions on either side ofsaid starting position, a pitman shaft disposed at substantially rightangles to said worm, a pair of spaced bifurcated arms secured to saidpitman shaft, anti-friction trunnions secured to and extending fromopposite sides of said nut disposed between the bifurcations of saidarms and in slightly spaced relation therewith, spaced arcuate meansmounted on said pitman shaft for preventing undue turning of said ballnut about said worm, and means for reducing the spaces between saidtrunnions and the bifurcations of said arms as said nut approaches saidstarting position.

8. Power transmitting means comprising, a worm, a nut mounted on saidworm and adapted for movement from a starting position on the latter topositions on either side of said starting position, a rock shaftdisposed at substantially right angles to said worm, spaced bifurcatedarms secured to said rock shaft, oppositely disposed trunnions on saidnut mounted in operative relation with said arms, one side of said nutlying in close proximity to one of said bifurcated arms whereby undueturning of said nut about said worm is prevented, and means foradjusting the space between said one side of said nut and the said oneof said bifurcated arms.

9. Power transmitting means comprising, a worm, a nut mounted on saidworm and adapted for movement from a starting position on the latter topositions on either side of said starting position, a rock shaftdisposed at substantially right angles to said worm, spaced bifurcatedarms secured to said rock shaft, oppositely disposed trunnions on saidnut mounted in operative relation with said arms, and widely spaced flatshoulder means on one side of said nut lying in close proximity to oneof said arms, whereby undue turning of said nut about said worm isprevented.

10. Power transmitting means comprising, a worm, a nut mounted on saidworm and adapted for movement from a starting position on the latter topositions on either side of said starting position, a rock shaftdisposed at substantially right angles to said worm, spaced bifurcatedarms secured to said rock shaft, oppositely disposed trunnions on saidnut mounted in operative relation with said arms, a flat extendedshoulder on said nut disposed at either side of one of said trunnions,said shoulders lying in close proximity to one of said bifurcated arms,whereby undue tuming of said nut about said worm is prevented, and meansfor adjusting the space between said shoulders and the said onebifurcated arm.

11. Power transmitting means comprising a worm, bearing means for saidworm, a traveling nut mounted on said worm and movable from a centralposition to positions at opposite sides of said central position, a rockshaft disposed at an angle to said worm, bearing means for supportingsaid shaft, arm means on said rock shaft, interengaging means on saidarm means and nut for actuating said rock shaft upon movement of saidnut in either direction from said centra1 position, and means allowingfor a predetermined amount of clearance between said inter-engagingmeans except in one position of adjustment of said nut.

12. Power transmitting means comprising, a worm, bearing means for saidworm, a traveling nut mounted on said worm and adapted for translationalmovement from a starting position to positions on either side of saidstarting position, a rock shaft disposed at an angle to said worm,bearing means for supporting said rock shaft, a bifurcated arm securedto said rock shaft, a trunnion mounted on said nut and disposed betweenthe bifurcations of said arm, and means allowing for a predeterminedamount of clearance between said trunnion and bifurcations except in oneposition of adjustment of said nut.

13. Power transmitting means comprising, a worm, a nut mounted on saidworm and adapted for movement from a starting position to positions oneither side of said starting position, a rock shaft disposed at an angleto said worm, an arm secured to said rock shaft, a portion of said armbeing disposed in close proximity to one side of said nut so as toprevent undue turning of said nut on said worm, interengaging means onsaid nut and arm whereby movement of said nut in either directionimparts movement to said rock shaft, and means allowing for apredetermind amount of clearance between said inter-engaging meansexcept in one position of adjustment of said nut.

14. The device set forth in claim 13 including adjustable means forvarying the distance between the said side of said nut and said arm.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 695,222 Mooers Mar. 11, 1902 698,407 Malicet et a1. Apr. 22,1902 998,611 Graef July 25, 1911 1,343,846 Rapson June 15, 19201,706,521 Bugatti Mar. 26, 1929 2,045,811 Twyman June 30, 1936

